Metal-coated colloidal crystal film as surface-enhanced Raman scattering substrate

A dipping technique was developed to coat colloidal crystal films with metals. It was found that nanosized metallic particles could be simply immobilized onto the monodisperse spheres in the colloidal crystal film. As one of the application of such films, silver-coated colloidal crystal films were used as the surface-enhanced Raman scattering substrates. Very large enhancements were observed. In addition, it was also found that the enhancement factor varies very little from place to place on a particular substrate and even on different substrates. It can be anticipated that such substrates will find wide applications in Raman analysis and Raman imaging.